Hi All:

   I found a solution for some artefacts I was suffering, and I thought
perhaps others can benefit from it too. Also, perhaps it can give clipka
some ideas, although I think he already knows the cause of these specific
artefacts.

   When using smooth meshes (mesh2) on scenes with high quality rad
settings, I noticed some black artefacts on curved parts of some meshes.
After two weeks trying everything you can think of, I discovered it was
caused by objects not present on the second pass!

   I use often the trick of "enhancing" the radiosity effect with some
objects which are present on the first pass, to save radiosity, but that I
take out on the second pass with an "if", because I don't want them to be
visible. With medium quality rad settings, the second pass doesn't seems to
suffer any artefacts. But if you crank up the settings, they appear more and
more, even if you are using the exact same settings on both passes.

   Fortunately, the solution is easy and even elegant: *don't take out the
objects on the second pass, just use "no_image" on them!* :)

   As I said, it seems related to smooth triangles, because the artefacts do
not appear on flat-normal versions of the same meshes. I think the real
problem behind it is described by clipka on his radiosity tutorial:

news://news.povray.org:119/web.495b9db71d584ee0483cfa400@news.povray.org

   Regards,

--
Jaime

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